Re: USB stack vs bus_dma_tag_t

[Frank Wille <frank%phoenix.owl.de@localhost>]

On Sun, 10 Oct 2010 08:30:56 +0200
Radek Kujawa <radoslaw.kujawa%c0ff33.net@localhost> wrote:

> error: expected specifier-qualifier-list before 'bus_dma_tag_t'
> 
> Brief look at the source gave me impression that:
> - Amiga port of NetBSD does not support MI DMA machinery
> - There's bus_dma_tag_t in arch/m68k but not in arch/amiga

Yes.


> - USB stack thinks that every port is capable of MI DMA
> - USB stack thinks that every driver does DMA transfers

Probably. Don't know for sure.


> How does bus_dma implementation of arch/m68k relate to arch/amiga?

It is not used yet.


> Can it be easily glued together to provide what I need? Ofcourse that
> would not bring proper DMA handling to amiga port, because it needs
> far more MD code.

I really hoped somebody else would have replied to this. I have never
done anything with bus_dma functions.

When you look at mac68k you just need to define a m68k_bus_dma_tag in
mainbus.c and pass the tag to all attached devices. The dma functions
are all defined in m68k/m68k/bus_dma.c.

I admit I have no idea how those functions determine if a memory space
is dma-capable or not. But it should be enough to make it compile.


-- 
Frank Wille